The entire disclosure of Japanese Patent Application No. 2000-394858 filed on Dec. 26, 2000 including specification, claims, drawings and summary is incorporated herein by reference in its entirety.
The present invention relates to a gas turbine combustion device. More specifically, the present invention relates to a method for reducing combustion oscillation in view of an acoustic problem, particularly to a method for reducing acoustic resonance.
FIG. 8 shows a conventional gas turbine combustion device.
In a conventional gas turbine combustion device as shown in FIG. 8, exhaust air from a compressor flows into a vehicle chamber 1 and further into a turbine through a combustion device 4 having an inner cylinder 2 and a tail cylinder 3.
FIG. 2a and 2b show a simplified gas turbine combustion device wherein a plurality of cylinder combustion devices 4 are arranged along a circular peripheral line. Each cylinder combustion device has an inner cylinder 2 and a tail cylinder 3. Thus, the vehicle chamber 1 and the combustion device 4 are acoustically connected.
As described above, in the conventional art, the vehicle chamber 1 and the combustion device 4 are acoustically connected in a system, wherein the combustion device 4 has a number of acoustic modes connected to a circular peripheral mode in the vehicle chamber 1 so that combustion oscillation occurs in any one of the modes.
When experimental combustion occurs in a sector (c) of one combustion device as shown in FIG. 2a, reproduced combustion oscillation is different from that in an actual vehicle chamber mode. Accurate reproduction in the actual vehicle chamber mode is difficult.
For example, as shown in FIG. 3a, there is shown an m-order nodal diaphragm (mND). If an n-order acoustic mode exists in the combustion device 4, the number of oscillations is mxc3x97n.
That is, the combustion device mode is related to the vehicle body mode. In the case that the value m of the nodal diaphragm is changed, its acoustic character is largely changed even if the value n of the acoustic mode is acoustically connected.
As shown in the following equation, a stable characteristic Ec of combustion oscillation is determined based on an acoustic mode shape and acoustic frequency at the combustion position. On the other hand, the vehicle chamber is a sector in the element experiment so that a circular peripheral mode in the vehicle chamber is not formed and the acoustic characteristic is different from that in an actual case.
Ec=xe2x88x92∫∫p(x,t)q(x,t)dxdt=xe2x88x92∫∫p(x) cos xcfx89tQ(x)cos {xcfx89(t+xcfx84)}dxdtxe2x80x83xe2x80x83(1)
Wherein, p, q, xcfx89, xcfx840 and xcfx841 is pressure, energy output, angular frequency, combustion system time delay and a supply system time delay, respectively. The following equation also applies; xcfx84=xcfx840+xcfx841.
As shown in FIG. 7, damping energy Ef becomes stable where Ec+Ef=Excfx84 greater than 0 and the damping energy Ef becomes unstable and, oscillation occurrs in the case of Ec+EF=Excfx84 less than 0. Q(x) and xcfx84 are only influenced by combustion elements and p(x) and xcfx89 are only influenced by acoustic elements.
Accordingly, in an oscillating model as shown in FIG. 9, the number of unstable regions are m (value of circular peripheral model) xc3x97n (value of combustion device mode).
For example, if a nodal diaphragm order along the circular peripheral direction in a vehicle chamber 1 is 4, and a 3 order acoustic mode is present in the combustion device 4, twelve unstable regions (4xc3x973) are present.
Accordingly, in the conventional gas turbine combustion device, combustion oscillation caused by thermal elements and acoustic elements is apt to happen so that the gas turbine combustion device is damaged.
To overcome the above problems, a gas turbine combustion device according a first aspect of the present invention comprises a plurality of combustion devices provided in a vehicle chamber in which each combustion device has an inner cylinder and a tail cylinder, and wherein each said gas turbine device has an acoustic sleeve between an outer cylinder and said inner cylinder.
A gas turbine combustion device according to a second aspect of the present invention comprises pores provided at a vehicle chamber side of the acoustic sleeve according to the first aspect of the present invention.
A gas turbine combustion device according to a third aspect of the present invention comprises a plurality of combustion devices provided in a vehicle chamber, in which each combustion device has an inner cylinder and a tail cylinder, a side wall having a porous structure is provided near an opening end of said combustion device at an upstream side.
In a gas turbine combustion device according to a fourth aspect of the present invention, a sintered metal mesh, a ceramic piece or a porous board is provided at an outer side of said porous board according to the third aspect of the present invention.
In a gas turbine combustion device according to a fifth embodiment of the present invention, a contraction in a flow path is provided near the opening portion according to the third aspect of the present invention.
In a gas turbine combustion device according to a sixth aspect of the present invention, a porous board is located at a position perpendicular to a combustion flow at an upstream side of the combustion device according to the third, fourth and fifth aspects of the present invention.
In a gas turbine combustion device according to a seventh aspect of the present invention, a board having a narrow slit instead of a side wall having a porous structure is provided near an opening portion of the combustion device at an upstream side according to the third, fourth, fifth and sixth aspects of the present invention.
FIGS. 1(a) and 1(b) shows a general view of a gas turbine combustion device according to a first embodiment and a second embodiment of the present invention;
FIGS. 2a and 2b respectively shows a end and side views of a conventional gas turbine combustion device;
FIGS. 3a and 3b shows a conventional acoustic model in a relation between a combustion device and a vehicle chamber;
FIGS. 4a and 4b shows an acoustic model of the present invention in a relation between a combustion device and a vehicle chamber;
FIG. 5 shows a general view of a gas turbine combustion device of the third embodiment of the present invention;
FIG. 6 shows a general view of a gas turbine combustion device of a fourth embodiment of the present invention;
FIG. 7 is a graph showing a relation between energy and a combustion condition in a field;
FIG. 8 shows a cross sectional view of a conventional gas turbine combustion device;
FIG. 9 is a graph showing a conventional actuating condition;
FIG. 10 is a graph showing an actuating condition according to the present invention;
FIG. 11 shows a general view of a gas turbine combustion device of the fifth embodiment according to the present invention;
FIG. 12 shows a general view of a gas turbine combustion device of the sixth embodiment according to the present invention;
FIG. 13 shows a general view of a gas turbine combustion device of the seventh embodiment according to the present invention;
FIGS. 14a and 14b show a general view of a gas turbine combustion device of the eighth embodiment according to the present invention;
FIG. 15 shows a general view of a gas turbine combustion device of the ninth embodiment according to the present invention;
FIG. 16 shows a general view of a gas turbine combustion device of the tenth embodiment according to the present invention;
FIG. 17 shows a reflective ratio; and
FIG. 18 is a graph showing an increasing ratio of an irradiation power at the opening portion caused by a resonance.